We propose to continue research directed toward the development and use of the intramolecular 1,3-diyl trapping reaction in organic synthesis. The proposal describes what one might refer to as a "second generation" of the diyl trapping reaction, one which leads to the formation of products other than the linearly fused tricyclopentanoid ring system. Specifically, we intend to focus attention upon the synthesis of the trichothecane antitumor agents trichodermol and verrucarol, the diterpene aphidicolin, as well as the tigliane natural products exemplified by the interesting tumor promotors, the phorbol esters.